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The absence of TGA codons in the DNA sequence of the Phytophthora megasperma gene for cytochrome c oxidase subunit II

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dc.contributor.advisor Hudspeth, Michael E. S. en_US Sachay, Donna Jean en_US 2016-03-04T20:00:01Z 2016-03-04T20:00:01Z 1989
dc.description Includes bibliographical references (pages [62]-69) en_US
dc.description.abstract Previous characterization of P. megasperma mitochondrial DNAs revealed two genic inversions between a host-specific and a nonspecific strain. As part of a characterization of oomycete mitochondrial genomes, studies of the nucleotide sequence of the region involving the COI-COII inversion were initiated. The COII genic region was localized, cloned and sequenced. The COII gene encodes a 258 amino acid protein with an approximate molecular weight of 29.6Kd. The data strongly suggests a lack of introns in this gene. The COI protein has been found to be encoded 235bp downstream from COII on the same strand. The translated COII amino acid sequence exhibits a greater than 50$ amino acid homology with other characterized eukaryotic COII proteins, being most homologous with those of plants. The two functionally conserved membrane-spanning helices and the putative copper-binding site, along with other conserved regions, have been identified in the protein. The genic region has an A-T content of 71$. Flanking regions contain 79$ and 90$ A-T contents. As expected for A-T-rich genomes, codon usage tables indicate a strong bias for the use of a third position A/T when choices exist. Of all codons within this gene, 85$ terminate in an A or T. Remarkably, however, all 7 Trp codons are TGG instead of the preferred TGA typical of all but plant mitochondria using a modified genetic code. This would lead to the conclusion that in Phytophthora mitochondrial DNA, TGA is either a stop codon, as it is in plant mitochondria, or an infrequently used trp codon. en_US
dc.format.extent [vii], 69 pages en_US
dc.language.iso eng en_US
dc.publisher Northern Illinois University en_US
dc.rights NIU theses are protected by copyright. They may be viewed from Huskie Commons for any purpose, but reproduction or distribution in any format is prohibited without the written permission of the authors. en_US
dc.subject.lcsh Cytochrome oxidase en_US
dc.subject.lcsh Cytogenetics en_US
dc.subject.lcsh DNA en_US
dc.title The absence of TGA codons in the DNA sequence of the Phytophthora megasperma gene for cytochrome c oxidase subunit II en_US
dc.type.genre Dissertation/Thesis en_US
dc.type Text en_US
dc.contributor.department Department of Biological Sciences en_US M.S. (Master of Science) en_US

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